FIG. 1 shows an exemplary frequency hopping base station radio, which is indicated generally at reference numeral 100. On the transmit side and receive side, the base station radio 100 generally includes two transmitter local oscillators 102, 104 and two receiver local oscillators 106, 108 that are connected to a transmitter switch section 110 and a receiver switch section 112, respectively. In particular, the first transmitter local oscillator 102 and second transmitter local oscillator 104 are respectively connected to a first transmitter switch 114 and a second transmitter switch 116. These transmitter switches 110, 112 are, in turn, connected to a third transmitter switch 118 that ultimately outputs transmitter local oscillator signals from the transmitter local oscillators 102, 104 to a transmitter mixer 120. Similarly, on the receiver side, the receiver local oscillators 106, 108 are respectively connected to a first receiver switch 122 and a second receiver switch 124, which are directly connected to a third receiver switch 126 that outputs receiver local oscillator signals from the receiver local oscillators to a receiver mixer 128.
As shown, at the transmitter side, a microprocessor 130 is used to provide a transmitter intermediate frequency signal to a transmitter intermediate frequency section 132 connected to the transmitter mixer 120. Taking both transmitter local oscillator signals from the transmitter switch section 110 and transmitter intermediate frequency signals from the transmitter intermediate frequency section 132, these signals are mixed to provide a transmitter mixed signal for output to a transmitter radio frequency section 134. The transmitter mixed signals are then converted to provide transmitter radio frequency signals for transmission via a power amplifier 136, a duplexer 138, and an antenna 140. On the receiver side, on the other hand, after adjustment of a received radio frequency signal through the duplexer 138, a low noise amplifier 142 forwards the received radio frequency signal to a receiver radio frequency section 144 that filters and amplifies the signal and outputs it to the receiver mixer 128. Specifically, the receiver mixer 128 mixes the receiver radio frequency local oscillator signal from the receiver switch section 112 and receiver radio frequency signal from the receiver radio frequency section 144 for output to a receiver intermediate frequency section 146, which filters and amplifies the intermediate frequency signal for output to the micro-processor 130.
It is well-known in the art that full duplex communications systems having a time offset between transmit and receive traditionally require base station radios to have extensive hardware, as described in FIG. 1, in order to provide fast-frequency hopping capacity. Emerging communication markets, however, demand low-cost, small-sized cellular base stations without sacrificing frequency hopping capability. Thus, conventional base station radios are inefficient in cost and size because of their extensive hardware associated with this requirement of both a transmitter local oscillator and a receiver local oscillator.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments of the present invention. Also, common and well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.